it is the top of the hour. i am jake tapper. i am in boston, covering the capture of the suspect in the boston attack and the investigation into it. boston celebrates the capture of

the last suspect in the marathon bombings and the town is trying to recover. they're playing at fenway park, boston red sox after postponing friday's game. but the investigation continues. now that the surviving suspect is in custody at a boston area hospital, however, 19-year-old dzhokhar tsarnaev did not give up without a fight. [ gunfire ] he and police exchanged gunfire as tsarnaev held police at bay in a watertown, massachusetts backyard. here is a cbs news photograph. he used a boat to shield himself in the final standoff. police say he was wounded, covered with blood. he was rushed to the hospital where he is now under guard. earlier we got the inside story on how the capture went down. wolf blitzer talked with the police chief of watertown in a revealing conversation.

let's take a brief listen. >> we had a couple thousand police officers on scene. the turnout was incredible, the support from the state and the region. we had the tactical people to close that seam down and secure it. we did take our time to make sure that everybody was safe in the neighborhood. and eventually used flash bangs. >> what is that? >> it is a loud compression that would stun somebody for a short period of time. and we began negotiations in a 15, 20 minute period, we were able to get him to stand up and show us that he didn't have a device on him. >> so he's lying in the boat, been there several hours, he's wounded clearly, right, he's bleeding. >> right. >> he's obviously weak. you come over there, what do you say to him. you have a bull horn, you say come out with your hands up? >> we have a negotiator, it was actually on the second floor of the house looking down at the boat. >> you could see him.

>> no, couldn't see him. there was a plastic top over them. we had the state police helicopter say when there was movement in the boat from the heat sensor. we could tell he was alive and moving. we began negotiations that way. and over a long period of time, we were able to finally get him to surrender. >> right now, there's heavy police presence in the boston hospital where the suspect is recovering after being seriously injured. elizabeth cohen is outside that hospital. elizabeth, federal prosecutors are inside. of course, the question, could the suspect be charged today? >> you know, that's a definite possibility, jake. our colleague, pamela brown, spoke to an official at the justice department and this person told her that they thought it was highly possible he could be charged before he leaves the hospital. of course, we don't know when that's going to be. we don't know how seriously he

is wounded or hurt. he's in serious condition, but that doesn't really necessarily tell you a whole lot. we are expecting an update on his condition, but i don't think we're going to get many details, just a one serious or stable. probably won't learn much about what actually is going on inside. jake? >> elizabeth, there's a photograph of dzhokhar tsarnaev after he was apprehended, it was from i think the bureau of alcohol, tobacco, firearms, a picture of him down, and he was being intubated, a tube being put in his mouth to help with his breathing. that would suggest that he was in bad condition there. explain to people when people say he's in serious condition but not critical condition, what exactly is the difference? >> reporter: critical condition often means someone's life is on the line, they're not really sure if he is going to survive.

it sounds like they feel that he is going to survive. certainly the fact he was intubated tells us something, tells us that this is not just, you know, a small thing, but the fact that it is serious enough, critical means he is likely to survive. >> all right, elizabeth, thank you so much. with the hunt over for the suspects, one dead, one in custody, investigators are focusing on the full puzzle. they want to find out what motivated these two brothers, described by many that knew them years before as normal, but they're certainly not normal. cnn analyst and boston globe columnist is here with me. we heard from the watertown police chief, told us it looks as though the suspects acted alone. how can they be so sure? >> i'm not sure we know exactly now what happened in the process, clearly between 2008 and now, especially with the older brother.

something changed over the course of the years. this investigation will lead to foreign travel abroad. >> the older brother, tamerlan was in russia in 2012. >> yes. >> six months. relatively recently. who did he meet with, what did he learn. what happened when they came back here. the investigation will take place here, was there anyone else here or any other aspects of the case that will help figure out the whys and hows that are important to us and of course abroad. there's a huge focus on both those parts, and it actually began wednesday when they were able to identify who the brothers were. >> it is impossible to think the older brother spent six months in russia and that had nothing to do with this. >> right. right now if you're looking at it from the facts that are known right now, maybe those six months did radicalize him and he learned techniques to come here. but i have been through enough cases, know enough about these

cases that i am cautious about sort of looking at what we know now, saying that was the moment. we learned so much about other terrorists or sociopaths weeks or months later. we spoke about columbine, everything we thought about the columbine killers, not to say that the brothers are similar, ended up being not true, years later. we all want to know the why. we want to determine if we can stop it again, that's the primary focus, stop future copy cats or other terrorists from doing this. the why may take a little longer than stopping them and the capture. >> very briefly, there was a national public radio report last night about an interview with the three roommates of the older brother's soon to be wife, girlfriend at the time, the three roommates said between 2008, 2009, that's when he seemed to become radicalized, talking about how islam was

under attack, criticizing his wife, demanding she wear modest dress, a hijab, if he went to russia 2012, it would suggest that 2012 wasn't necessarily when everything went wrong. >> right. and that's going to be -- there have been home grown terrorists, radicalization internally. i know this is scary for americans to think there are people here from all over the world who can be disruptive, but one way to look at this is some of the successes of counter terrorism efforts have -- means there will be people who do bad things, but they're not going to do sort of horrific crisis things like 9/11. so in some ways we talk about resiliency, the city, baseball games being played, people complain about the weather, i feel like we are back to normal, when you talk about resiliency, it is also anticipating this could happen again, and learning from the investigation and response. >> thank you. speaking about complaining of

the weather, it is freezing, what is going on, it is april. a lot more to go on this. thank you so much. we will talk to you later today. it is one of the most visible signs of boston, beginning to heal. fenway park as juliette mentioned is alive with red sox fans cheering on the hometown and home team. jb, you there? >> reporter: i am here, jake, indeed. it is warming all our hearts at fenway to be here with 35,000 brothers and sisters now. it has been an unbelievable day. it began with a special ceremony before the game when we saw victims of the attacks in the boston marathon, saw first responders, and saw a remarkable thing. we heard it, too, the entire crowd sang the national anthem again in unison. that has become a new boston tradition. one i think that will truly stick. i spoke to a number of fans here who came to this game. they said it was very, very special for them to be here.

i think none more so than this woman i met who was actually from the town of watertown. yesterday she was locked down, sheltering in place. today she's at fenway. let's listen to what she said. >> so surreal an experience. it was like this morning i woke up and i was like i am so grateful that i don't have to wake up feeling like i did yesterday every day. felt totally lucky to be a resident of watertown and citizen of this country. >> reporter: a lot of people have these signs here that say boston strong. i think in one of the moments that will resonate a long, long time here, david ortiz, the red sox designated hitter took the field before the game and in front of the live crowd and live television audience watching said this is our bleeping city. and as you can imagine, jake,

the place went nuts. >> i am wearing that red sox hat on again, i want you to know. one quick question. have you seen an increase in security? pat downs, metal detectors? >> absolutely. there was a long line. i am outside gate b, these are the cheap seats, but some of the best seats, you come to the bleachers, sit in back, watch the game. there was a long line well after the game began. they were giving extra pat downs. i saw much greater security presence than i've ever seen here. >> john berman. thank you so much. digital forensics, how something as simple as a cell phone is making a big difference solving big cases. coverage continues from boston. stay here. ♪

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welcome back to cnn's continuing coverage of the terrorist attacks in boston. investigators got a big break on this case, thanks to volumes of videotape and photographs from that deadly day in boston. surveillance cameras and images on cell phones and other mobile devices have proven that digital forensics is the way of the future. proguess or gary kessler is a digital forensics expert. don clark, former special agent for the fbi that worked the world trade center investigations. gary, how much are investigations using cell phone images and calls. >> incredible number, particularly criminal investigations rely on cell phones and computers. digital devices certainly in the last 10 and 20 years have become

increasingly either the target or the instrument and or the record keeper of criminal activity and other nefarious activities. so being able to look at what's on the digital devices becomes incredibly important. mobile phones in particular, i don't have one with me now, but mobile phones in particular as we more and more of us are using android devices and iphones and other smart phones, it is essentially a portable internet terminal, and so not only do i have traditional call history and contact list and text messages, e-mail, browser history, gps and other information and other information we thought of on a desktop or camera is now with us all the time. >> don, i want to ask you about digital technology. before i do, there's something about the fbi that i want to pick your brain about. we found out yesterday that the

fbi had already one time before interviewed tamerlan tsarnaev because in 2011, russia, the foreign government the fbi is discussing, russia asked the fbi, going to read from the fbi's press release for information about tamerlan tsarnaev. the request stated it was based on information he was a follower of radical islam, a strong believer, and that he had changed drastically since 2010 as he prepared to leave the united states for travel to the country's region to join unsp unspecified groups. they checked to look for things like derogatory telephone communications, online sites associated with promotion of radical activity, association with other persons of interest, travel and education plans and history. they interviewed family members. the fbi didn't find any terrorism activity and those results were provided to russia in summer of 2011. i think a lot of people are

curious in learning that he was on the fbi's radar and then apparently just dropped off the fbi's radar. the fbi right now i'm sure is gathering information on this to find out more. put this in context for us. >> well, i wouldn't say that they just dropped off his radar, but i would think that during the course of this that someone had to -- the fbi had to obtain some information from someplace or another that caused them to look into this individual, no matter who that individual may have been, and i would suspect that they did a very detailed investigation on what they knew and were able to gather based on the request that might have been made to them about this particular individual, and in doing so they did not come up with any information that they thought was harmful in some way and therefore apparently the case was closed and moved on.

>> all right, don and gary, stick around, we're going to come back to you. right now we have to take a break. cnn's continuing coverage of the terrorist attacks at boston continues. lots more to cover on this. we'll keep the discussion going with both of you. we'll be right back. ♪

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and we've received numerous high ratings for our excellent standard of care. we're focusing on the big things so you can enjoy the little things. kaiser permanente. thrive. welcome back to cnn's continuing coverage of the terrorist attacks in boston. we want to pick up where we left off on how something as simple as this, mobile phone, can make the difference catching criminals and solving big cases like the boston terrorist attacks. back with me, professor gary kessler and former fbi special agent don clark in houston. don, many people complain about the cameras on city blocks, boston is something of a surveillance city.

big brother watching. but does living in the digital age make it easier to catch criminals? >> well, i think it certainly assists, you know, because you have the cameras and things out there, and let's face it, we're in an era now where we're going to live with these cameras and they're there, and they do serve a good purpose. and i know there are people that say i don't want everybody watching me and this, we all don't, but the bottom line is that they're there, and they're there to stay, and we also know that they are used as protection devices as well. and there have been a number of people that's been saved and there's been a number of buildings saved and so forth simply because there was an opportunity for cameras there and to be able to see something that someone could be able to stop something before it happened, so i'm not opposed to the cameras. i'm certainly not suggesting that cameras ought to be looking into private citizens as to what they're doing directly without a

warrant. however, in terms of protections of buildings and facilities and that type of thing, i think it is a great idea. >> gary, we hear about photos being enhanced, the quality being enhanced, either in photo stills or video. what kind of techniques are used to enhance a photograph? >> certainly there are a number of mathematicalal goe rhythms that can be used to take the information that's already in the image and filter out if you will, they're filtering out the noise, and they're enhancing what sharpness we can find and trying to build on stuff we know is there and good information. i think interestingly, of course, the quality of the photos that we're able to get from digital cameras is, of course, incredibly better than it has been in years past. the quality of photos we can get

from our cell phones actually the cell phone that i have takes better pictures than my digital camera, probably because the digital camera is three years old. to don's point, people do appropriately express concern if a municipality wants to put up a new camera at say a traffic intersection, and they want to be sure that the government is not intruding on our privacy and those kind of things, and increasingly what we're missing again as don alluded to, everybody is walking around in addition to everything else with a camera and we're taking pictures. in the case of boston with the idea of what they call crowd sourcing, law enforcement was able to ask people to voluntarily give up information to help them in an investigation that law enforcement could have never compelled the population to have given up. >> all right, gentlemen, thank you so much. professor gary kessler in

florida and former special agent don clark in houston, thank you so much for joining us. we are waiting for the surviving suspect to be charged, then the real work begins. we will hear from the man that prosecuted the shoe bomber on how he thinks they will build a case against the alleged boston marathon terrorist. we know the value of your at ueducation of phoenix is where it can take you. [now arriving: city hospital] which is why we're proud to help connect our students with leading employers across the nation. [next stop financial center]

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what's this one do? i dunno. may i respond negatively about your porcelain poodle? this should be in the trash. score planner is free to everyone. free score applies with enrollment in freecreditscore.com fancy bear slider still in beta. welcome back to cnn's continuing coverage of the terrorist attacks in boston, i am jake tapper. the surviving suspect in the boston marathon attack has not yet been charged with anything but that could happen any time. the work then will be to build a case against him. mike sullivan joins me, former u.s. attorney and former acting director of the atf. mike, you were the one that prosecuted richard reed, the shoe bomber. looking at the